I am sure it is possible not to know if you break your water. It can be as small as a little trickle or a huge gush, and many women think they be leaking urine. So my question is.... what if I sleep through labour?

Usually, once the water breaks, the woman will go into labour within 24 hours of the breaking. I reckon the contractions will signal to you that you are having your baby and it is quite unlikely that you will sleep through the process. So, in the meantime, do get as much rest as you can. :)